chapter 5—part 1 ocean circulation/ upwelling zones/ el niño
TRANSCRIPT
![Page 1: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/1.jpg)
Chapter 5—Part 1
Ocean Circulation/Upwelling Zones/
El Niño
![Page 2: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/2.jpg)
Ocean Circulation
1. Eckman spiral
2. Upwelling zones
3. El Niño
![Page 3: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/3.jpg)
• Ocean surface currents are driven by atmospheric winds
• Energy from wind transferred to water by friction
![Page 4: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/4.jpg)
Wind
Wind moves surface water (friction)
Velocity of water decreases with depth
![Page 5: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/5.jpg)
But
• Both the wind and the ocean currents are deflected near the atmosphere-ocean interface by a combina- tion of the Coriolis effect, friction, and gravity
• This gives rise to what is termed the Eckman Spiral - Surface wind rotated 45o relative to the
geostrophic (free troposphere) wind- Surface waters move 45o relative to the surface wind direction- Net transfer of water 90o to the surface wind
![Page 6: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/6.jpg)
The Eckman Spiral
![Page 7: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/7.jpg)
• Surface waters move 45o relative to surface wind• Net transfer of water 90o to surface wind direction
Eckman Pumping
Equator
Surface windSurface currentNet ocean transport
• Surface water is driven offshore by Eckman spiral• Replaced by water from below upwelling!
Geostrophic wind(Easterlies)
![Page 8: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/8.jpg)
Consequences of upwelling
• Deep water is rich in nutrients (P, N, Fe)
• Upwelling brings nutrient-rich water to the surface ocean, fueling biological productivity (phytoplankton)
• Zooplankton eat the phytoplankton
• Fish eat both of these get good fisheries in upwelling zones
![Page 9: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/9.jpg)
El Niño (the Christ child)
Every 3-7 yearsLast 6-18 monthsHappens near Christmas season
![Page 10: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/10.jpg)
El Niño (the Christ child)
Every 3-7 yearsLast 6-18 monthsHappens near Christmas season
Opposite:
La Niña (the girl child)
![Page 11: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/11.jpg)
Normally…
Warm waters pushed by trade winds towards Asia and Australia
Cold waters upwell near South America
![Page 12: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/12.jpg)
http://www.ldeo.columbia.edu/dees/ees/climate/slides/ocean_index.html
Pacificwarmpool
![Page 13: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/13.jpg)
Normal Conditions:
http://www.enn.com/specialreports/elnino/what.asp
• This east-west circulation pattern, which is sort of like a Hadley cell, is called the Walker Circulation
•It reinforces the normal tropical easterlies, thus helping to foster upwelling off the coast of Peru
Australia/Indonesia
South America
![Page 14: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/14.jpg)
Normal Conditions:
El Niño Condition:
http://www.enn.com/specialreports/elnino/what.asp
NormalWalker Circulation
WeakenedWalker Circulation
South America
South America
Australia/Indonesia
Australia/Indonesia
![Page 15: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/15.jpg)
Atmospheric Pressure:
Normal high over Tahiti, low over Darwin, Australia
El Nino low over Tahiti, high over Darwin
The shift in pressure is called the Southern Oscillation
The combined El Niño/Southern Oscillation isreferred to as ENSO
![Page 16: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/16.jpg)
Atmospheric Pressure:Normal high over Tahiti, low over Darwin, AustraliaEl Niño low over Tahiti, high over Darwin
* Darwin
![Page 17: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/17.jpg)
Southern Oscillation Index
[ Pdiff - Pdiffav ] SOI = 10 ----------------------- SD(Pdiff) where
Pdiff = (average Tahiti MSLP for the month) – (average Darwin MSLP for the month),Pdiffav = long term average of Pdiff for the month
in question, andSD(Pdiff) = long term standard deviation of Pdiff
for the month in question.
http://www.bom.gov.au/climate/glossary/soi.shtml
![Page 18: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/18.jpg)
StrongEl Nino
![Page 19: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/19.jpg)
![Page 20: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/20.jpg)
La Niña
http://www.bom.gov.au/climate/current/soi2.shtml
• Is this what is caused the 2011 Texas drought?• “ENSO neutral” conditions persisted during most of 2012
![Page 21: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/21.jpg)
• The fact that we have been in an extended La Niña may explain why the climate has not warmed as fast as expected over the past 15 years…
![Page 22: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/22.jpg)
Total heat accumulation in sea, land, and air
http://www.skepticalscience.com/clarifying-continuation-global-warming.html
![Page 23: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/23.jpg)
Results of El Niño
In the Pacific Region:
weaker trade windswarm waters across the Pacificrain in South America, drought in Australia
![Page 24: Chapter 5—Part 1 Ocean Circulation/ Upwelling Zones/ El Niño](https://reader030.vdocument.in/reader030/viewer/2022032707/56649e255503460f94b14d37/html5/thumbnails/24.jpg)
Results of El Niño
In the Pacific Region:
weaker trade windswarm waters across the Pacificrain in South America, drought in Australia
Teleconnections--shifting atmospheric patterns (global)
high rain in the US midwestmore storms in the Pacific, fewer in the Atlanticheavy rains in Californiacold winters in the Northeastern US